Posted on July 21, 2020 by admin
Um, what???? Yeah…. I sawed a lithium battery in half. With zero fires. Pretty insane. I’m basically a ballr. The need for sawing a battery in half arose while working on the electric moped. FSAE had several 1.6kWh packs which had weird issues, namely that they *occasionally* would short out to their cooling plates. Not hard shorts, just a few hundred kohms- but this is enough that they would slowly discharge, and more importantly, fail the rigorous isolation tests in FSAE rules. Therefore, these packs were not suitable for racecar duty, which meant that they were generously donated to the
Posted on July 8, 2020 by admin
Once or twice a year, something special happens. Something you don’t normally see. Something so incredible, its worth writing a blog post about: The members of MITERS go outside. Hear Ye, Hear Ye: its time for the legendary, certifiably insane, MITERS BOATING ADVENTURE. That time of year when we use our big brains to make magical machines which defy physics by not sinking and occasionally exhibiting forward motion. Usually, every boating adventure revolves around a “main event” of Dane’s creation, such as the Doom-Winch or the boat named Three Wave Rectifier. However, this year a different scheme was proposed: the
Posted on June 5, 2020 by admin
Today Aaron and I made a shed/greenhouse! Last year, Aaron bought a little cheapo greenhouse to store his boat stuff in, which promptly collapsed under the weight of the New England snow. The original greenhouse consisted of a metal frame (which broke) and a plastic covering, which we decided to reuse. We started with a simple CAD model. The dimensions were largely set by the plastic covering. The width was slightly under 10′, and the height was 7′. How high to make the walls was a source of debate. The original plan was to go with a low 40″ wall,
Posted on May 30, 2020 by admin
A while ago I bought a bunch of cheap 128×64 OLED screens off eBay to attach to random things. They were cool but I never really progressed to using them in actual projects. But in this time of Corona quarantine, I decided to give the screens a go again. It is pretty easy to find arduino libraries for these screens. I wasted no time porting one of the simpler libraries for use on an STM32F401, mostly just changing it to use the mbed I2C calls. This proved to be actually somewhat annoying, but eventually with some aggressive scoping and reading
Posted on April 26, 2020 by admin
Hey all, this project has been a long time in the making. Here goes. Over my senior year, I built the electric bike, which somehow turned out to be awesome. I estimate it has been over a thousand miles, and it has literally never left me stranded- not once. It’s small enough to fit on the commuter rail, yet produces enough torque to literally do a backflip. It is the perfect fun city ride. Yet, the electric bike does leave some things to be desired. Over the summer of 2019, I decided on some features that I wanted in a
Posted on April 14, 2020 by admin
Today I decided to decided to turn on the CORDIC in my STM32G431 and compare its speed at calculating sines and cosines to the sinf() function in the math.h library. I also decided to evaluate the performance of how we can use the CORDIC to more quickly calculate the DQ transforms when doing motor control. First up: evaluating sinf. We declare a float s and assign it to the value of sinf(theta). We measure the time it takes by scoping PA_7. Here is the code: The results of this were interesting. sinf takes a surprisingly variable amount of time to
Posted on April 10, 2020 by admin
A while ago I bought some STM32G4 nucleos, with the intent to eventually switch to them for my motor control needs. The G4 series is ST’s newest line of micros, incorporating the rich set of analog peripherals of the F3 series with the clock speed of the F4 series. The G4s have on average more memory than the F3 series, but not as much as the F4s. Here are the datasheets of the three previous micros I have used extensively and some of their features: STM32F303K8: 72 MHz, 64 Kb flash, 16 Kb RAM, dual 5 MSPS ADCs, Ultrafast Comparators,
Posted on April 3, 2020 by admin
Its coronavirus season, which means NO MITERS. RIP. Last week I grabbed my sourdough starter out of the fridge and we shut miters down for the long winter. Back at my apartment with no CNC mill, I’ve been up to exclusively software projects. It turns out my list of software “back burner” ideas is actually quite long, and the insideness has given me a fair amount of time to work on projects from this list. Notable items from this list: Lookup table interpolator firmware for multiple bus voltages Motor controller firmware re-organization because it is currently a garbage fire Boost
Posted on March 24, 2020 by admin
Back in high school I made a wood fired evaporator out of sheet metal. I called it “The Ecraperator” for obvious reasons. Over a random weekend I had some time to go back home and fire it up again. Here it is, ready to be lit, with my dad for scale. Its lit!! The maple syrup goes in a tray that was left over from my grandpa’s maple syrup days. The ecraporator itself is just a box with a piece of dryer vent attached to the back. The long chimney helps provide a strong draft. So in my high school
Posted on March 24, 2020 by admin
About 4 years ago Mike gave me a Ryobi 25CC weed wacker. I have always wanted to make it into a generator to to make a range extender electric vehicles. I hid the weed whacker in various places around MITERS hoping one day I’d have the time to make my dream a reality. In the fall 2019, the time finally came. The weed whacker was mated to my original Prius A/C motor. This motor is very overkill and can easily out-torque and out-RPM the weed whacker, but its what I had. The motor was mated to the weed whacker through
